| 摘要 |
PROBLEM TO BE SOLVED: To improve a welding quality by varying the frequency of a power source which oscillates at the secondary side of an inverter AC resistance welding machine or the like in accordance with the variation of a welding condition. SOLUTION: An excessive variation of the electric current while energizing for a welding is suppressed by varying the frequency of a power supply depending upon such welding conditions as the plate thickness and the material of a welded work at the method of an inverter AC resistance welding where an AC electric power supplied from a commercially available AC power supply 1 is rectified through a rectifier circuit 2, the electric power rectified by the rectifier circuit 2 is converted into a smooth DC electric power by a smoothing filter circuit 3, the DC electric power derived from the smoothing filter circuit 3 is converted into a high frequency AC electric power by a switching control of a switching element group 5 of an inverter circuit 4, the high frequency AC voltage derived from the inverter circuit 4 is applied to the primary side of a welding transformer 6 of a resistance welding machine, and the welded work is pressure-welded by supplying an AC electric current whose form is trapezoidal or similarly trapezoidal with a commercially available power supply frequency necessary for the welding upon an welding electrode on the secondary side of the welding transformer 6.
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